Democratic Republic of Congo says M23 rebels attacked positions near Bunagana town and several other areas of North Kivu province, "supported by soldiers and artillery from the Rwandan army."
Regional authorities in eastern Democratic Republic of Congo (DRC) have said Rwandan soldiers and artillery supported attacks by the M23 rebel group, accusing Rwanda of seeking to occupy the DRC's border town of Bunagana.
The office of the governor of North Kivu province said on Sunday DRC forces had repelled early-morning attacks by M23 rebels, backed by Rwandan forces, near Bunagana and elsewhere.
"The goal pursued by Rwanda is to occupy Bunagana in order not only to asphyxiate the city of Goma but also to put pressure on the Congolese government," it said in a statement.
The violence pushed over 25,000 people to flee the area, with thousands escaping to neighbouring Uganda, the United Nations humanitarian agency OCHA said.
DRC's accusations are part of an escalating dispute between the neighbours that has revived old animosities. Rwanda denies backing the M23 offensive.
The Rwandan government could not immediately be reached for comment. It denies playing any role in M23's recent attacks, but has echoed M23 charges that DRC is cooperating with the Democratic Forces for the Liberation of Rwanda (FDLR), an armed group run by ethnic Hutus who fled Rwanda after taking part in the 1994 genocide.
On Thursday, DRC accused Rwanda of sending 500 commandos in disguise into eastern DRC.
On Friday, the countries accused each other of firing rockets across their shared border. DRC army said one strike killed two children.